suppose that a severe drought, characterized by extremely low levels of rainfall for an extended period, hit a grassland region that spans two states in the united states. in fact, across the affected area rainfall amounts were 65% lower than normal over a three-year period. researchers had been recording the species composition of two communities in the grassland region for a number of years, and they continued to do so during each year of the drought and for five years following the drought. one of the communities was on the eastern side of the grassland region and the other community was on the western side. the multi-year data recorded by the researchers revealed that plant species richness was approximately equal in both the eastern and western grassland communities before the drought. by the end of the three-year drought, over 50% of plant species had died in the eastern community, but only 15% had died in the western community. furthermore, in the first year following the drought, when normal levels of rainfall had resumed, species richness in the western community had returned to its original, pre-drought value. however, it took four years for species richness in the eastern community to be restored to its original, pre-drought value. based on these findings, the researchers concluded that relative to each other, the eastern community displayed resistance and resilience to a severe, three-year drought, and the western community displayed resistance and resilience.